This research program project includes the following studies: 1. Normal development of the nervous system in humans, to be carried out on the embryos and fetuses of the Carnegie Collection and on others to be collected, and including detailed studies of: (a) the normal sequence of development of the central and peripheral nervous system, skull, vertebrae, and limbs in staged embryos, so as to provide an accurate morphological base for the analysis of congenital defects and malformations. (b) The growth and maturation of the fetal nervous system, skull, vertebrae, and limbs, especially with respect to the downgrowth of tracts such as the pyramidal through highly organized and functioning brain stem and spinal cord. Again, particular attention will be paid to correlation with congenital defects and malformations. 2. Normal development of the nervous system in non-human primates using the material of the Carnegie Collection and the California Primate Research Center, and including studies of normal development of embryonic and fetal brain, including interpeduncular nucleus and eye. 3. Teratological studies. These will be carried out at the California Primate Research Center and will include: (a) Experimental teratology, focusing on anencephaly and myelomeningocele, and (b) mechanisms of teratogenesis in the central nervous system of rhesus monkey embryos. 4. Development of a computerized catalogue of prenatal primate material. 5. Clinicopathological studies. These will be carried out mostly at the Sacramento Medical Center, will focus on the establishment of a laboratory for the study of human congenital defects and malformations, and will correlate with the morphological and experimental studies. 6. Planning for future projects: These are presently under discussion.